Artificial horizon



Aug. 17, 1943. L; F CARTER 2,326,835

ARTIFICIAL HORIZON Filed Jan. 9, 1941 INVENTOR 4 B LESLl F. CAR ER l-us ATTOIIRNEYI Patented Aug. 1 7, 1943 j -ABTIFICIAL 7 Leslie F. Carter, Leonia,

Gyroscope. Company,

N; J., assignorto. Sperry 1111)., Brooklyn, Y. a

corporation of New York a r Application January 9, 1941,ScrialNo.-373,765

' gene (01. sea-204 For ordinary flying, it is desirable that aslight change in the fore and aft inclination of the craft about its lateral axis be shown up quickly and noticeably by the horizon indicator. mentioned patent achieves this result by interposing a suitable linkage in the connections be The aforee tween the gyroscope casingand thearm. carrying the horizon bar, so that-a greatly'magnified or amplified movementoccurs-during the-:first few degrees of tilt of the craft either upwardly or'downwardly. In that patent, howeventhe exaggerated or amplified movement gradually.

decreases upon further tilting 'of the rotor case."

ing from the vertical,. so that the movement of the .baris not uniform over the visible scale;- An object of the present invention is to provide an artificial horizon having an exaggeratedbut uniform scale for indicating the firstfew degrees of tiltof the craft, but in which the indicator bar is restrained from moving out of sight or on the scale regardless of all ordinary, gyrations of the airplane, so that a further object of the invention is to provide means for achieving thisend'while permitting the use of a uniformly graduated scale; M

Afurther object of the invention isto provide means foradjusting the horizonbarwith respect to the pitch indicating sca1e.

Referring to'the drawing, illustrating thew preferred form of my invention, Fig. 1 is a plan view (partly in section) of .the

tions only of the casing being showjnt Fig. 2 is a side elevation of the same, also partly in section. 7

Fig. 3 is a perspective view of the horizon bar, a portion of the gimbal ring, and a portion of the rotor bearing member.

Fig. 4 is a fragmentary side elevation showing improved artificial horizon thefore and aftapor the relative position of the horizon bar and they horizon bar actuating member when said bar has been moved to the top of the pitch scale.

Fig. 5 is a face view of the instrument.

In the drawing, the artificial horizon is shown in conventional form, the same being'enclosed in an outer casing I, only the fore'and aft ends of which have been shown. .In practice, this casing is usually in the-form of an air-tight con tainer from which air is exhausted. The casing is provided witha transparent front window 2 through whichthehorizon bar 3, the bank-angle rotor (not 'shown) is spun within thecasing IE on i a normally verticalaxis' by any suitable means, such as an ail-"jet, the air emerging through four slots I3 in the lower portion of the 'casing, with which pivoted pendulums Hi cooperate toerect the gyroscope as'well understood in the art. As an additional feature of 'the'invention, there is provided a bafiie adjustment ring having a pa-ir'. of auxiliary bafiies or'spoilers it and i6 adjustablein acircurnferential' direction forcontrollingthe'jifore and aft "jets. As explained in my-prio'r Patent. 2,219,295, dated October 29, 1940; for Pneumatic erection devices for gyro.- scdpesgby means of these spoilers, the rate of erecting moveme'nts'fof the rotor about the fore and aft axis during turns may be decreased,

whereby errors tresulting'from-"the effect upon the fore and aft pendulums of' turning of the craftxmay. belreduced. Ithas been found that 7 similar auxiliary:bafiiesjorspoilers' are. not re quired for controlling the rate of erectingmovei. j .ments of.;;the' rotjor. about the-lateral axi since i the .pitch'pendulums are not affected by, centrifua H gaI.-forces. .-*I.preferQtherefore, to leave the'erecj-v tion forces" of the lateral, jets} fully effective: to

7 keep the erection period fairly rapid. A curved,backgroundmember 2a. is shown gas secured to an arm. projecting-from the gimbal-;

' ring-1'. isaidbackground member may be pro-f f vided with an'index membenfijfiiFig. 5). readable] onz the" aforementioned scale. 5 around the, pe?. riphery of the-front. window to indicate relative tilting of the'rotorfcasingand craft 'aboutithe J fore and aft axis of the gyroscope.

Projecting from the side ofthe rotor bearing casing in to the rear ofjpivot i2 is apin H which extends through an annular slot w in an enlarge-' ment I9 of gimbal ring 1; Said pin carrie a circular in cross-section withth'e fiat portion facingrearwardly. "The horizon bar sis carried on an arm 4 whichis shown as pivoted at 24 to the The actuating! arm 20f gimbal ring I and is provided with a counterbalancing weight 25 beyond the pivot. The axis of pivot 24 is parallel to the lateral axis ll, l2 of the rotor bearing ring, and weight 25 is arranged to normally maintain arm 4 in thehorizontal position. t a

According to the present invention, pin 23 is spaced a substantial distance from lateral axis II, II, being somewhat nearer pivot 24, so that during. initial movement of actuating arm 20- from the horizontal as a result of turning of the craft about its lateral axis, the main component transmitting connection between the cooperating horizon bar member and its actuating member. s

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawingshall be interpreted as illustrative and not in a limiting sense.

, Having described my invention, what I claim "and desire to secure by Letters Patent is:

of the motion imparted to arm 4 by engagement of pin 23 with'slot 26 will be a lifting motion or,

alternatively, a depressing-motion, as the case may be. Sincethe horizontal component of the motion of pin 23 is very small during the time said pin is in engagement with slot 26, it will be be seen that the motion of arm 4, and conse- 'quently the motion of horizon bar 3, will vary at substantially the same proportional rate v as the rotor bearing casing tilts about axis ll,' l2, this permitting the use of a uniform'pitchscale 22.

Also, because of the long radius'of pin 23 from pivot I2 and the short arm 2324 compared to the length of arm 4, the initial movements of said rotor casing ID are considerablyamplified by horizon bar 3. Thus, while the rotor casing .tilts about axis H, l2'througha few degrees, the horizon bar moves to the outer limit. of the uniform scale 22.

In order to terminate the indicatingmotion of horizon bar 3 before'it has exceeded the range of scale '22; bar 4 is provided with two arcuate cam surfaces 26a, 26b,lthe center of curvatureof each of which, respectively, will substantially coincide with the lateral or transvere axis 1|, l2 of the "rotor bearing member or casing 10 when engaged by pin 23. In other words, when arm 4 has been elevated or loweredby rotation of pin 7 1. In an artificial horizon for aircraft, a rotor and a rotor bearing member, a gimbal ring having a transverse axis upon which said rotor bearing member is pivotally mounted, an outer casing having a fore and aft axis upon which the gimbal ring ispivoted, a neutrality balanced horizon bar member pivoted about a transverse axis on the rear portion of the gimbal ringand having an indicating portion spaced'remotely from said pivot, andan actuating pin for said bar member spaced. radially from the lateral axis of the rotor bearing member and extending in a direction 23 in engagement with slot 26 to a position V wherein pin 23 disengages said slot, the center of curvature of cam surface 2611, or 2617, as the case may be for either position'of' arm 4, will substantially coincide'with the axisl I, I2 about which pin 23 rotates. These surfaces intersect slot'zfi. at the points where the edge of pin 23 highest'and lowest indicating positions. Move- ,ment of pin Bibeyondthispoi'nt,'due'to' further tilting-of rotor bearing case i0, causes the flat surface atthe end of said pin to'engage surface 25a or 26b (see Fig. 4) 'Further rotation of. pin

23 about pivot l2 imparts no elevating or depressing force to bar 4because of the shape of cam surfaces 26a and 26b. :Stop members?! and 28 arefprovided'as' positive limitsof the range of motion of bar 4 and also to prevent jarring or vibration of the bar when in either of its-extreme posi- ,tions; Such constructiondefines a limited motion parallel to said axis, said bar member having a short open end slot adapted to engage the said pinduring initial movementof the horizon bar member, said slot merging into a pair of arcuate surfaces having their center of curvature, 1 respectively, substantially -coincident with the transverse axis of the rotor bearing member when engaged by said actuating pin and posi- 'tioned so as to engage with the moving pin when the rotor bearing member has tilted beyond the predetermined indicating range.

2. In an artificial horizon for aircraft, a rotor and a rotor bearing case, a gimbal ring having a transverse axis upon. which said rotor bearing case is pivotally mounted, an outer casing having a fore and aft axis upon which the gimbal ring is pivoted, a horizon bar member pivoted about a transverse axis on the rear portion of the gimbal ring, said bar including an open-ended engages said slot when the horizon bar'3 is at its angles of tilt greater than said predetermined angle to efiect relativelylittle angular' mo'vernent of the barmember. v 1 3. An artificial horizon as claimed in claim 2,

V in which saidactu'ating member is provided by a crank arm having a pinwhich form's'the slide portion thereof.

LESLIE F. CARTER. 

